A malocclusion is a condition where teeth exist in a certain relationship varying from an ideal. A Class 2 malocclusion describes malocclusions that are skeletally as well as dentally based. In a Class 2 malocclusion, various bones, including those of the cranial base, cause positioning of the teeth resulting in a Class 2 molar relationship. In a Class 2 molar relationship, a maxillary first molar lies either directly over or in front of a mandibular first molar. This is in contrast to a "normal" or "ideal" occlusion wherein the maxillary first molar lies slightly behind the mandibular first molar.
Prior art provides a number of devices for the correction of malocclusions. For example, the prior art has used face bows. Face bows are wire springs attached to an appliance in the mouth to provide correcting force to the appliance. Elastic traction is provided by an elastic or retractable member attached to the head or the neck by strap or cap. The limitations of this approach are well known in the art.
An alternative method also well known in the art is a method of using bite blocks to provide restoring force for correcting the malocclusion. FIG. 1 shows an example of the bite blocks of the prior art as disclosed in U.S. Pat. No. 4,619,609 to Clark, issued Oct. 28, 1986. FIG. 1 shows upper and lower bite blocks 17, 21 with a wire retaining mechanism. The prior art provides a means for attachment of an inner bow 10 to an upper dental arch. This attachment means comprises a molded palate plate (not shown) having wire retainers (not shown) for connection of the palate plate to the upper teeth. The wire retainers receive and retain free ends of the inner bow 10, thereby accomplishing positioning of the bow. The palate plate incorporates a bite block 17 at the posterior side. The upper bite block 17 has a rearward and downward angled surface 18. The upper bite block 17 is positioned over the occlusal surfaces of the upper buccal teeth. A lower dental arch (not shown) conforms to the inner profile of the teeth of the central lower dental arch. Molded into the lower dental arch are spring fixing wires, for attachment to the mandibular teeth, as well as rearwardly directed wire hooks 19, for attachment of an elastic traction member 20. The bite blocks 17, 21 act to promote mandibular displacement between the upper and lower dental arches.
Prior art orthodontic appliances used to treat Class 2 malocclusions are designed to correct a malocclusion specific to a patient at a specific time of treatment. As the malocclusion changes over a period of time, the prior art appliance becomes obsolete. Since prior art devices are not adjustable for treatment of such skeletally based malocclusions, the present state of the art requires that new appliances be created and applied during the progression of a given patient's treatment. This necessity of creating multiple appliances precipitates less sensitive and less effective treatment, and contributes to higher costs for orthodontic treatment.
It is therefore the motive of the invention to provide, for treatment of Class 2 malocclusions, an orthodontic appliance that may be adjusted as treatment progresses.